Automatic cut-off



'.(No Model.) N. W. TWISS.

AUTOMATIC GUT-OPF. No. 247,588. Patented Sept. 27,1881.

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s UNITED STATES PATENT OFFICE.

NELSON W. TWISS, OF NEW HAVEN, CONNECTICUT.

AUTOMATIC CUT-OFF.

SPECIFICATION forming part of Letters Patent No. 247,588, dated September 27, 1881.

Application filed July 28, 1881. (No model.)

To all whom it may concern:

Be it known that I, NELSON W. TWIss, of the city of New Haven, State of Connecticut, have invented a new and useful Improvement in Automatic Gut-Offs for Steam-Engines, of which the following is a full, true, and exact description, reference being had to the accompanying drawings. I

On the llt-h day of February, 1879, Letters Patent of the United States, No. 212,285,vrere granted to me for'improvement in cut-o gearmg.

My present invention relates to an improvement upon said apparatus so patented to me. I refer to that patent for a full description, the improvement only being shown iu the present application. In that patent the steam was admitted and exhausted from the steam-cylinder by a steam-valve having a cylindrical face and suitable ports, and the steam was cut oli" by an interior trip cut-oft' valve having likewise a cylindrical face traveling upon the inside of the steam-valve. This valve was tripped ata suitable position by a cam and closed by means of a spring. In order that such valve should close rapidly a spring of considerable tension was requisite, and it was found that a considerable resulting jar occurred. l have therefore devised a traveling dash-pot moving with the main valve and adapted to arrest the movement ot' the trip cut-oit' valve.

My drawing represents a vertical elevation on the side of the apparatus, showing the movable dash-pot.

L represents the arm controlling the cut-o valve, which valve is movable independently oit` the main valve. The main valve is operated, as before, by the link F2. 'lhe arm B moves with the main valve, and upon it is supported the dash-pot D. Pivoted to the arm operating the cut-o valve, at the point A, is the rod C, connected with the moving part of the dash-pot l). As soon as the hook P is tripped, as described in the previous patent, the spring L tends to throw the arm L to the left, and the motion of this arm is arrested by thedash-pot D. This dash-pot, being supported upon the main valve and moved with it, is al- Ways in the proper position to arrest the movement of the cut-ott valve.

It will be seen that my invention may also be applied to ila-t slide-valves having an independent cut-oft valve sliding upon them but it is particularly applicable to double rotary valves, as shown.

It is obvious that the location of the dashpotmay be greatly altered.

What I claim as my invention, and desire to secure by Letters Patent, is

l. The combination, with a main steamvalve, of an independent cnt oft' valve and a movable'dash-pot carried by the main valve and adapted to arrest the movement of the cut-oft' valve at any point at which it may be tripped, substantially as described.

2. The combination ot' a rotary steam-valve, a rotary cut-oli" valve for cutting oft' on the back of the steam-valve, and a dash-pot partaking of the motion of the steam-valve and adapted to arrest the movement ot the cut-off valve at any point at which it may be tripped, substantially as described.

3. The combination of a rotary steam-valve, a rotary cut-oli valve cutting 0E on the back of said rotary steam-valve, an adjustable trip adapted to trip the cut-oftl valve at different points of the stroke, and a dash-pot partaking ot' the movement ot' the steam -valve and adapted to arrest the movement ofthe eut-off valve at its point ot' trip, substantially as described.

NELSON W. TVVISS.

Witnesses:

ANTHONY GEEF, Jr., GEO. H. EVANS. 

